Compounding Hotline

Martin A. Erickson III, RPh

Published Online: Monday, December 1, 2008

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Mr. Erickson is director of professional affairs at Gallipot Inc.

I want to compound antibiotic female urethral inserts in a polyethylene glycol (PEG) base weighing 700 mg each. Is a disposable mold available? Also, the vehicle formulation I have (PEG 1450 and PEG 300 [9:1 and 20:1]) tends to melt in our climate. By adding some PEG 4000, it takes more than half an hour to melt. Do you have any suggestions? What are disadvantages of vaginal inserts based on glycerin-gelatin or on PEG?

Disposable urethral molds can be made from commonly available materials. Consider the patient's sex: female urethral inserts (bougies) are about 0.5 mL; male bougies are about 1.7 mL. One method: cut the end from a tuberculin or other 0.5- or 1.0-mL syringe, polish the cut end, and pull in molten material to the appropriate dose volume.

Another method: cut a thin plastic straw to the desired length, depending on patient's sex. Be sure to tare these molds for accurate dosing. In each case, remove the hardened urethral insert material by slightly warming the mold and pushing the insert out of the mold. For modified syringe molds, simply dispense each syringe as a unit of use, counseling the patient to use it as an "inserter." Trochibase might be an appropriate vehicle (it contains acacia as a binder); it consists primarily of PEG 1450, which is soft, but refrigeration will decrease stored dose melting.

PEG dissolves in body fluids to release ingredients. Instruct patients to run tepid water briefly over the insert to start dissolution, coat liberally with a water-based personal lubricant (K-Y, Wet, etc) to ensure presence of water, then insert. For the syringe mold, lubricant placed on the end of the syringe before administration can serve the same purpose; use the empty syringe to insert additional lubricant. Vaginal inserts of glycerin-gelatin can melt quickly and can be difficult to handle/insert. As an alternative to PEG, use vegetable oil base, such as a fatty acid blend, which melts to release active ingredients.